To date, 13 patients with Alzheimer's disease and 6 healthy elderly subjects have completed a placebo controlled trial of intravenous physostigmine followed by a double-blind crossover trial of oral lecithin administration (20 grams of 80 percent phosphatidyl choline). The preliminary results of this ongoing study indicate that: 1. Plasma choline levels correlate highly with lecithin intake, and that lecithin ingestion does not produce any clinical or hematologic side effects. 2. A comparison of lecithin and placebo scores, both of patients with Alzheimer's disease and of healthy elderly subjects, shows that memory-test performance during lecithin ingestion was either the same as or inferior to performance during placebo ingestion in most instances. However, on verbal paired-associate learning, 4 patients with Alzheimer's disease obtained substantially higher scores while taking lecithin than they did while taking the placebo. In addition, some family members and friends of these patients reported favorable changes in daily behaviors during lecithin but not during placebo ingestion. These findings suggest that the beneficial effect of lecithin treatment might be selective with respect to person and task. 3. The optimum dose of physostigmine necessary for enhancing memory function varies across subjects; the relationship between response to physostigmine and response to lecithin is unclear. We now are measuring spinal fluid levels of the dopamine metabolite HVA, the serotonin metabolite 5-HIAA, and the norepinephrine metabolite MHPG. These data could help us identify particular neurotransmitter abnormalities in individual patients, and thus, permit more specific treatment with the particular neurotransmitter precursor, whether it be lecithin (for serotonin), or tyrosine (for the catechnolamines).